Microtome



March 3, 1959 F. SJCSTRAND ET AL 2,875,669

' MIQROTOME Filed Nov. 2, 1955 3 Sheets-Sheet 1 Fig. 2

Jmm m b m QM A 4 PM March 3, 1959 F. SJOSTRAND ET AL 2,875,669

MICROTOME 3 Sheets-Sheet 2 Filed Nov. 2, 1953 March 3, 1959 F. sJsTRAND ET AL 2,875,669

MICROTOME} Filed Nov. 2, 1953 3 SheetsSheet 3 Fig.4

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United States Patent 2,875,669 MICROTOME Fritiof Sjiistrand, Stockholm, and Emil Ferdinand Giirtler,

Bromma, Sweden, assignors to LKB-Produkter Fabriksaktiebolag, a company of Sweden Application November 2, 1953, Serial No. 389,719 Claims priority, application Sweden November 6, 1952 3 Claims. (Cl. 88-40) The present invention relates to a so-called microtome,

i. e. an apparatus for slicing specimens for microscopy.

The previously known microtomes have comprised an object holder arranged to reciprocate in a guide or the like, and a knife, arranged in the way of the object and secured to one wall of a container, filled with a suitable liquid, in which the sliced specimens are collected. For feeding the object during operation, it has been common to use the thermal expansion of a bar, which has either been heated slowly during operation, or has been heated in advance and is allowed to cool slowly during operation.

It is one drawback of these well-known microtomes that the object on returning will touch the knife and make it vibrate, which will cause an unequal thickness of the specimens. Besides, the surface of the object to be cut may be damaged when the object on returning rubs against the knife. Nor has it proved to be possible to avoid the drawbacks caused by the vibrations by shortening the knife, particularly on cutting very thin specimens, and if a razor blade is used as a knife, such a shortening makes it impossible to use the whole edge of the blade but only a very small portion of it.

To avoid these drawbacks the microtome according to the invention is constructed in such a manner that the object during operation always passes the knife in the same direction, and that the knife is arranged so that practically the whole of its edge can be utilized. For that purpose the object holder according to the invention is arranged eccentrically in a rotating cylindrical member which constitutes the rotatable journal member of a journal bearing of the slidable type, means being provided for preventing any axial displacement of the journal and the holder for the knife is shaped in a curve to give the edge of the knife the shape of an arc with a comparatively great radius. This curved shape increases the stability of the knife, vibrations being thereby avoided. The object, being eccentrically supported, will move circularly and will thereby always strike against the knife in the same direction. i

The object holder is mounted upon a feed bar which passes slidingly through a bore in the journal, the bore being located parallel to the axis of rotation of the journal and eccentric thereto, and it is therefore evident that it is not possible to use the same means for feeding the object as has been used in older apparatuses, as heat would be transferred from the heated feeding bar to the bearing disk, which would expand and jam. To avoid this drawback, the feeding bar is divided into two parts, which are connected by means of a casing or the like of a material with a low heat conductivity, e. g. a synthetic resin. On heating the part of the feeding bar which is thus insulated from the bearing journal, the desired feeding is obtained without the bearing journal being heated.

The invention will now be described more in detail, with reference to the accompanying drawings, which for the purpose of illustration show one embodiment of the 2,875,669 Patented Mar. 3, 1959 invention. In the drawings, Fig. 1 is a side-view of the apparatus. Fig. 2 is a cross sectional elevation of the container for collecting the specimens and the holder for the knife. Fig. 3 is a horizontal view, partly in section. Fig. 4 is a vertical front view of the object holder with its bearing device, the holder and the adjustment device for the knife. Fig. 5 shows in a smaller scale an overall view of the apparatus with a driving motor, a fan and a microscope for adjustment.

The object 2 to be sliced is mounted in a holder 4, one end of which is constructed as a nut with an even number of sides, capable of being inserted and fixed into a casing 6 with flat opposite inner walls. The holder 4 is secured in the casing 6 by means of a screw 8, and the casing may be secured in a desired position to one external and of one longitudinal part 10a of a two part feeding bar 10 by means of a screw 12. The second part 10b of the bipartite feeding bar is provided with an electric heating coil, indicated at 14, energized through sliding contacts 16 and circular current carrying rails, indicated at 18. The rear end of the first bar section and the front end of the second bar section of the feeding bar are connected in a non-contiguous manner by means of a screw bushing 20 of a heat insulating material, e. g. Plexiglas or other suitable synthetic resin.

A comparatively thick cylindrical member 22 rotatable about its axis is provided with a through bore 22a extending parallel to the axis of the member 22 and eccentric thereto and section 10a of the feeding bar 10 extends through the bore 22a in sliding engagement with the bore wall. Section 10a of the feeding bar carries the casing 6 and object holder 4 with such a degree of eccentricity relative to the axis of rotation of the cylindrical member 22 that it is necessary for the object always to approach the knife in the same direction and to be in contact with the knife only during the slicing. At its other end the feeding bar section 1% is connected by a screw 24a to a disk 24 which is concentric to the cylindrical member 22 and connected to it also by means of two other shafts or bars 26 and 28 for stabilizing the construction. At the end of the feeding bar section 10b which is connected to the disk 24, a heat insulating spacer 30 may be provided between the endface of the bar and the disk.

As best shown in Fig. 3, the cylindrical member 22 includes a journal portion 22b rotatably mounted in a stationary bearing sleeve member 32 and also a peripheral V-shaped groove 22c for receiving a V-belt 34 which is driven by a motor 36. The member 22 is restrained against axial displacement by means of an integral peripheral flange 22d located between groove 22c and the corresponding end face 32a of bearing sleeve 32, the flange 22d running in sliding contact with the end face 32a. A collar 73 surrounds the opposite end of the journal portion 22b and serving as another flange on the member 22 engages the opposite end face 32b of bearing sleeve 32, the collar 73 being secured to the journal 2215 by means of one or more set screws 74. Consequently, the cylindrical member 22 is restrained against axial displacement by means of the flange 22d and collar 73 which engage the opposite end faces of the bearing sleeve 32.

The driving means for the cylindrical member 22, i. e. the belt 34 is not located in the plane x-x of symmetry of the bearing sleeve 32 but rather is situated at a distance from that plane. Consequently, owing to the tension in belt 34, the upper portion of flange 22d and the lower portion of collar 73 will be caused to bear against the corresponding portions of the end faces 32a and 32b of the bearing sleeve 32, whereas, there may be a slight play between the upper portion of collar 73 and the lower portion of flange 22d and the corresponding end faces 32b and 32a of the bearing sleeve 32. Thus the cylindrical member 22 performs a steady and regular rotation which is important for satisfactory operation of the microtome.

The slicing knife may be a razor blade, the edge of which has been sharpened against an even glass plate. This knife or razor blade 38 is secured between a holder 40 and one wall 42 of the container 44 in which the specimens are collected. Said wall 42 and the surface of the container 40 which is in contact with the knife 38, are curved as is illustrated in Fig. 3. Accordingly, the knife when secured, will be bent in a curve, and thereby its stability and resistance against vibrations will increase essentially. The knife is secured between the holder 40 and the wall 42 by means of two screws 46. The container 44 and the knife holder 40 are secured in slots 48 in an arm 50, pivoted by a shaft 52. The container with the knife holder are secured in the slot 48 by means of screws 54, and-the arm 50 may be secured against the shaft 52 by means of a screw 56. The shaft 52 is carried by a slide block 58 which is movable in two directions by means of a screwing device 60. The slide block 58 runs on a slide rest 62, mounted on a rotatable disk 64, which can be secured in a desired position by means of a locking device of a suitable kind, known per se, e. g. an eccentric 66. The disk 64, instead of being rotatable round a pin, which is perpendicular to the shaft 52, may of course be replaced by a second slide block which is movable perpendicular to the slide block 58 by means of a screwing device. As will be understood from this specification, the knife may be moved towards and from the object 2 by means of the slide block 58 and may be turned in two directions, perpendicular to each other, by means of the arm 50 and the disk 64. The object holder 4 may be secured in different positions in the casing 6, which may also be turned in different positions, and therefore the object may be secured in all possible positions relatively the knife, so that every desired specimen may be sliced.

For facilitating a correct adjustment a microscope 68 may be provided as is illustrated in Fig. 5. For obtaining a more rapid cooling of the feeding bar after one specimen has been sliced and before the next specimen is to be sliced, a fan 70 may be provided.

The apparatus works in the following manner.

The object to be sliced is embedded in a suitable resin in a manner known per se, and the specimen block is prepared to fit in the object holder 4, in which it may be secured by means of a screw 72. See Fig. 3. The object holder is then secured in a suitable position in the casing 6, and then the edge of the knife is adjusted to the desired angle relatively the outer end of the object. The knife is then moved so near the object, that slicing may begin. Said movement is accomplished by means of the screw 60 and is controlled by means of the microscope 68. Then the heating device and the driving motor are started. The rotating object will be fed for- ,wards continuously owing to the thermal expansion of one part of the bipartite feeding bar. The bar is heated to 5060 C. during a period of about 20-30 minutes. The length of the heated part of the feeding bar and the speed of rotation of the object are adapted to give a desired thickness of the specimens. By limiting the degree and time of heating as has been described, it is possible to use for the feeding only the straight part of the time-temperature-curve of expansion. It has proved possible with the apparatus according to the invention to slice specimens with a thickness down to about tions from the motor to be transferred to the microtome, thereby disturbing the slicing.

What we claim is:

1. In a microtome, the combination comprising a support, a holder for an object to be sectioned, a stationary knife holder mounted on said support and provided with a knife for sectioning the object, a cylindrical member, means mounting said cylindrical member on said support for rotation on its axis, means restraining said cylindrical member against axial displacement, said cylindrical member being provided with a through bore arranged eccentric to its axis of rotation and parallel to such axis, a feeding bar constituted by first and second metallic bar sections arranged in end-to-end but non-contiguous relation, a rigid connector of heat insulating material rigidly joining the rear end of said first bar section with the front end of said second bar section, said first bar section being mounted in said eccentric bore in said cylindrical member for longitudinal sliding movement in contact with the bore wall, means supporting said object holder at the front portion of said first bar section on one side of said cylindrical member, said connector for said bar sections being located on the opposite side of said cylindrical member, heating means disposed in heat transfer relation with said second bar section for heating the same to cause it to elongate in the direction of said connector and first bar section thereby effecting longitudinal displacement of said first bar section and said object holder relative to said knife, and means for. rotating said cylindrical member thereby to rotate said feeding bar sections and object holder and the object carried by the latter past said knife to cut sections from the object.

2. A.microtome as defined in claim 1 wherein said means restraining said cylindrical member against axial displacement comprises axially spaced flanges engaging the end walls of a bearing sleeve in which said cylindrical member is journalled for rotation, and said means for rotating said cylindrical member comprises a peripheral belt-receiving groove in said member axially displaced from said flanges.

3. A microtome as defined in claim 1, and which further includes a disc secured to the rear end of said second bar section, said disc being rotatable with said cylindrical member, and said disc including on its rear face circular current carrying rails concentric with the axis of rotation of said cylindrical member, and wherein said heating means comprises a coil surrounding said second bar section and connected to said rails.

References Cited in the file of this patent UNITED STATES PATENTS 766,135 Bausch July 26, 1904 1,798,447 Behrman Mar. 31, 1931 1,865,539 Pietzch July 5, 1932 2,155,523 Bausch Apr. 25, 1939 2,651,326 Kahler Sept. 8, 1953 2,753,761 Hillier July 10, 1956 FOREIGN PATENTS 654,123 Great Britain June 6, 1951 

